We're open for Clearing
The University of Law ranks 10th in the UK for quality of teaching in National Student Survey 2024. Find out more


Four major personality theories in psychology

Understanding ourselves and others is one of the most important aspects of psychology. As the subject involves scientific study many theories and concepts have developed to help explain why we act and think the way we do. Below, we take a look at four major approaches to understanding personality and how they inform the fascinating world of psychology.

By Grant Longstaff. Published 19 September 2023.

Trait theory

Before we look at specific theories we first need to look at trait theory – one of the most common ideas when it comes to studying personalities. Trait theory suggests our personalities are comprised of several inherent qualities – a set of simple traits – and the power of our response to these traits. Ultimately, how these traits connect and influence one another gives birth to a personality.

Five Factor Model of personality

The Five Factor Model (FFM), primarily developed by Paul Costa and Robert McCrae, is built upon the “Big Five” personality traits. These include:

  • Openness to experience
  • Conscientiousness
  • Extraversion
  • Agreeableness
  • Neuroticism

Often referred to by the acronym OCEAN or CANOE, each factor represents a sliding scale of personality types. Take extraversion for example. On one side of the scale, you’ll find attributes like quiet or unfeeling, and at the other talkative and passionate. However, it’s unlikely you’ll find many people at the extreme ends of the scale. In reality, most of us will exist somewhere in between.


The HEXACO Model, developed by Michael Ashton and Kibeom Lee, has much in common with the Five Factor Model. However, it does define the “Big Five” differently in places (with emotionality replacing neuroticism) and introduces a sixth factor; Honesty-humility. Honest-Humility aims to examine sincerity, fairness, and self-interest.

Both the Five Factor Model and HEXACO are assessed through a Personality Inventory. This is a questionnaire which requires people to report their feelings, motivations, and reactions to a variety of situations. The results can offer valuable insights into both personality and disposition.

Eysenck’s PEN Model

Before psychologists embraced the “Big Five” personality traits, Hans Eysenck created a model with only three universal traits. These were Psychoticism, Extraversion, and Neuroticism. Eysenck initially only focused on two traits, believing people had two personality dimensions: introversion/extraversion and neuroticism/stability. However, after working closely with his wife, Sybil, he added psychoticism which aimed to examine impulsiveness and aggression. Whilst his work has since been criticised and much developed upon, it’s important to recognise how his work – and his scientific approach in particular – has shaped modern psychology.

Type theory

With its origins in ancient Greece, type theory was developed and popularised by Carl Jung during the 20th century. At its core, type theory suggests there are only a limited number of personality types. Generally, type theories are much more restrictive than trait theories and are open to modern criticism as a result.

Myers-Briggs Type Indicator

One notable, yet controversial, type theory was developed during the 1940s by Katharine Cook Briggs, and her daughter, Isabel Briggs Myers. Both women were fascinated by the writings of Carl Jung and his work played no small part in the development of the Myers-Briggs Type Indicator (MBTI). The Myers-Briggs test asks a series of questions about behaviours, made up of four different scales, the results of which will assign you one of 16 predetermined personality types.

Whilst the Myers-Briggs test may reveal certain aspects of your personality you haven’t before considered, it doesn’t offer much in the way of scientific precision. Our Senior Lecturer in Psychology, Mark Jellicoe, said the MBTI “is often criticised and thought to be low in validity and reliability.”

The personality theories we’ve discussed here are just the tip of the psychology iceberg. If you choose to study psychology with us you’ll have the chance to explore personalities and individual differences and discover so much more about yourself and those around you. What are you waiting for?


Take a look at our range of undergraduate and postgraduate psychology courses and enrol today.